Blog Post
As a long-time Angeleno, I’m no stranger to hazy days and pollution soaked sunsets, but this past December felt different. The air was thick, smothering the city in a gray blanket that lingered for weeks. I found myself wondering—was the pollution actually worse, or was I just noticing it more? When I returned to UCSB for the winter quarter, I decided to dig into the data to understand what was happening.
1 Exploring Air Quality Trends
I began by exploring air quality datasets from the EPA, focusing on the annual median Air Quality Index (AQI) for Los Angeles County. While reviewing long-term AQI trends, I became curious about the specific pollutants driving poor air quality. By calculating the average frequency of each pollutant over time, I found that PM2.5 was the dominant contributor, responsible for 49% of air pollution, followed by ozone at 42%. Other pollutants, including NO₂ (7%), CO (1%), and PM10 (1%), played a smaller role. This discovery led me to ask a new set of questions: Where is PM2.5 most concentrated? What are its major sources? And how has it changed over time?
To answer these questions, I created an infographic that could visually communicate both spatial and temporal trends.